Mr Barnett would not detail the proposals for the northern suburbs, but said it involved a “better and more far-reaching proposal” and it was high on the Government’s list of priority projects to be announced “a few months later”.

Public transport woes, road congestion and planned, then cancelled, light rail for when Perth reaches 2.5 million residents by 2030 have dogged the eight-year-old Government.

Last month, Transport Minister Dean Nalder confirmed the $1.8b billion Perth-Mirrabooka light rail promised at the 2013 State Election would not go ahead.

Earlier, the Advocate revealed a fast bus lane, replacing a 2008-promised and then cancelled rail line to Ellenbrook, would be funded by scrapping a $40m realignment of Curtin Avenue in Mr Barnett’s electorate of Cottesloe.

Mr Barnett said the Mirrabooka light rail “simply became unaffordable” to do at the same time as a $1.9b train line to Perth Airport, after Federal Government funding switched from rail to roads following the 2013 State Election.

He also blamed falling mining royalties and less GST income on the change.

“We didn’t mislead the public, we just couldn’t deliver on that when we made that commitment in good faith, genuinely believing it was possible,” Mr Barnett said.

Opposition transport spokeswoman Rita Saffioti said Labor’s Metronet plan would extend the Joondalup rail line to Yanchep, and build a line to Ellenbrook.

“We also want to introduce circle bus routes the across the northern suburbs, linking the Joondalup Line with the core centres in the north east corridor,” Ms Saffioto said.

The Opposition claimed neither new line relies on Federal funding, but more of the Metronet plan will be announced closer to the March 2017 State Election.